Electrical switch



May 6, 1947- R. M. BLEAKNEY ET A1. `2,420,028

ELECTRICAL SWITCH Filed April 10, 1942 WW/1' A A A A l A A l A' A A A Aj...

ATTORNEY Patented May 6, 1947 .T ENT 0. FF If Albuquerque,

.. Mex., assignorsv to theUnitcd` Stoicsof AmericaV as rcorosintesir bv` the Score! .tary of the. New

Application April 10, 1942, Seralfllo. .438,5i6'` Zlaims- 1'Iglnsfinvention relates to electric switches, and. in: particular, toan improved switch of` the so called inertia type, in which the circuitContact; members .thereof are .operated as,` switch ,body is subieotedtoacceleration @ne application oifour invention is-tofanprdie nanceprojectile within wirlich` the` switch may be installed? fory thepurpose of4 closing an elec-H tric circuit-for detonating a powderycharge with?. inthe projectile asethe Vlatter isaccele-ated upon` beingmedi-rom, a gun. it will be. understood, however, that: o-u-r improvedswitch may bel uti;-V lized'fonotherapplications.andthat the appendedclaims-.shouid'be so construed.`

An` object; of our invention 4is to. provide an improvedL typeot:inertia. switch in which the switch` contaos: will be closed` andlocked, inf their l closed: position as` the switch is; subjected to ac.celeration.

Another object of; our. invention is. to provide.

an inertia.ty1pe.switch in` which an incr-tia. contantimemberisrinitially-spaced from a` iixed con?. tact member. byv anextensible tie member, the. latter member being extended as. theswitci-i` is.` subjectedto, aV predetermined' degree. of: accelera?,`tion, permitting the, lined.` and inertia contact members to l movetowards. and .engage each other.

Another object is to provide aninertia oper.- atedswitchiawhichwthe-inertia contact member is initially spaced apart fromthe xed contact member by a t i`e.member. of ductile material, which,when the switch is subjected to a predetermineddegree` of accelerationwill elongate to permit the inertia Contact member to engage the xedcontactmembee of the switch.

A further object is to provide an inertia operated switch in which aninertia contact member is-` in-itiallzgrl spaced apa-rt from the fixedcontact member by a Closely coiled. tie member which Will be elongatedas the switch ismsubjected to a pref determined degree ofelongationgpermitting:the switch contact members to engage each other...

Sti1l-another object ofour invention is to provide an inertia switch inwhich the inertia contact member is initially spaced apart from theiixed contact member by a closely coiled tie mem ber of ductilematerial, the latter being permanently elongated as the switch issubjected to an acceleration, thereby permitting the fixed and inertiacontact members to engage each other.

Another object is to provide an inertia operated switch utilizing acupped Xed contact member and a cylindrical inertia contact membermovable into engagement therewith, one of the contact members beingprovided with means for locking. the two together upon.- their;`cheesesment.

These and other objects; oi` ourfinyentionwill become more apparent fromthe detaileddescrip?. tion to follow and from the drawn-lgs,V in; which:

Fig. 1 is a central longitudinal section of a. preferred embodiment of:our improved; inertia operated switch when. in: its: Open-C` .Guit 1195ition, the partsbeing shown in elevati n;

Fie. 2 isa similar viewi` showing; theswitohin: its closedgcircuitposition;

Fie. 3 is a, oontralloneitudinal. section taken on the line 3 3 of Fig.1, the parts again being shown in elevation;

Fig. 4 is a crossesection takenv ontheline fie-4. ofi-Eig. 1';

Fig. 5 is a perspective viewof the movable con-sf tact member; and

Fig. 6A is a cross-section taken on the line 6 6- of Fig. 2.

Referring now to-the drawings, the switch comA prises a support memberl0 which may be made of any suitable` insulating material. IncludedWithinvsupportrnember I0 is anopening I'2` com-A posed of a series ofaxial bores |3y i4; I 5 andv 125, the last of which communicates with anoutlet passage FI, The bores I3V to i6 are preferably or progressivelysmaller diameters, thereby producing aV succession of stop shoulders`I8, IQnandy 20;

A tubular member 2| which, inthe present em bodiment, is made of;metallic material,v is/pro-V videdwith an upper;portionzZ-Zsand aAlowerportion 23pf-s-malle;` diameter providing anosetlk which is adaptedto seat upon shoulder` 13",., The bottom face ofthe tubular; portion-23.` rests. more shoulder i9.

' The iixed contact oi our. switch comprises a cupped. member 25. may beof copper or Someother. suitable electrically Conductive material,andsrositi nedwithintne bore mythe bottoinoi the. contrastinguoonshoulder 2o. The open top of member 25' is chamfered at 26 and isspaced at 21 from the bottom of tubular section 23.

A conductor 23 may be soldered or otherwise secured to the bottom of thecupped contact member 25 and may be led out of the switch body throughpassageway il. A similar conductor 29 may be likewise secured to thebody of a copper sleeve 3i? which is secured within the tubular section22.

The metallic sleeve 38 is formed with oppositely positioned lugs 33 atthe bottom thereof. The ends of the lugs are secured together to form aclosed loop to which is attached a bight portion 34 formed at one end ofa closely coiled helix 3| which, in the present embodiment, is made of ahighly ductile material such as soft copper.

The inertia contact member of our switch is a solid cylindrical member32 which is provided with oppositely disposed axial grooves 39. An openlink member 38 which is metallic and preferably resilient is securedtocontact member 32 by the grooves 39. A bight portion 4|] of the link 38is coupled to a complementary bight portion 35 formed at the bottom endof tie member 3|.

The inertia contact member 32 has a tapered surface 36 formed at thebottom to permit unimpeded entry into the cupped contact member 25 andone end 4| of the link member 38 is bent so that it projects beyond thecylindrical surface of contact member 32. Thus when contact member 32enters cupped member 25, the projecting end portion 4| will score theinside of the cupped contactI as at 42 and lock the contact members 32and 25 together.

The operation of our switch will be obvious. Assuming that the switch isinstalled on the inside of aprojectile, the contacts are in the positionshown in Fig. 1, while the projectile is in a rest position. When theprojectile is fired from a gun, however, the acceleration of theprojectile and hence the switch will cause the inertia contact member 32to exert a force upon the coiled tie member 3| in accordance with theequation Force-:MassXAcceleration Being of a ductile material, thelatter will be axially extended until its shape is substantially asillustrated in Fig. 2, permitting contact member 32 to enter cuppedcontact member 25 and complete a circuit between conductors 2B and 29which may be provided to detonate a powder charge within the projectile.This circuit has not been illustrated as it does not form a part of ourinvention.

The size of the wire constituting the coiled tie member 3| and theinternal diameter of the coil together with the combined masses of thecyl- 11' inder 32 and link member 38 will of course be determined by thedegree of acceleration involved. `For example, where accelerations areof the order of 8,000 g, g being equal to the acceleration due togravity, we have found the fol- .l

lowing to be satisfactory:

1. Tie member 3|-soft copper-diameter .020"- internal diameter of coil.040"-5 turns 2. Link member Sli-beryllium copper-diameter 3. Combinedmass of contact member 32 and link member 38:275 milligrams While theembodiment of our invention which has been described represents apreferred form of our invention, it will be evident that modications andchanges therein may be made by those skilled in the art withoutdeparting from the spirit and scope of our invention and from theappended claims.

Having thus set forth and disclosed the nature of our invention, what isclaimed is:

1. In a projectile including an electric circuit therein, an inertiaswitch carried internally of said projectile for controlling saidcircuit comprising a support, a cupped fixed contact member carried bysaid support, a complementary cylindrical contact member adapted to bereceived in said cupped contact member, a coiled ductile tie member, oneend of which is connected to said support and the other end to saidcylindrical contact member for initially spacing said contact membersapart, said cylindrical contact member being movable when saidprojectile is subjected to a predetermined degree of acceleration toaxially extend said tie member and enter said cupped contact member, andlocking means carried by one of said contact members to lock saidcontact members together as said contact members move into engagementwith each other.

2. In a projectile including an electric circuit therein, an inertiaswitch carried internally of said projectile for controlling saidcircuit comprising a support, a cupped fixed contact member carried bysaid support, a second complementary inertia responsive cylindricalcontact member adapted to be received by said xed contact, said secondcontact member including a pair of oppositely disposed axial groovestherein and an open link member carried in said grooves with one end ofsaid link member projecting beyond the cylindrical surface of saidsecond contact member, and a coiled ductile tie member, one end of whichis connected to said support and the other end to a bight portion ofsaid link member to initially space said contact members apart, saidsecond contact member being movable when said projectile is subjected toa predetermined degree of acceleration to axially extend said tie memberand enter said cupped contact member whereby the end cf said link memberprojecting beyond the cylindrical surface of said second contact memberwill score the inner surface of said cupped contact member, causing saidcontact members to be locked together.

ROBERT M. BLEAKNEY. EVERLY J. WORKMAN.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,336,828 Edwards Apr. 13, 1920FOREIGN PATENTS Number Country Date r188,175 French 1935 602,624 French1925

